Hybrid Simulations of Ground Motions from Local Earthquakes Affecting Hong Kong

2007 ◽  
Vol 97 (4) ◽  
pp. 1293-1307 ◽  
Author(s):  
K. Megawati
Keyword(s):  
Hong Kong ◽  
Ground Motions ◽  
Local Earthquakes ◽  
Hybrid Simulations

Broad-band ground-motion simulation of 2016 Amatrice earthquake, Central Italy

2020 ◽  
Vol 224 (3) ◽  
pp. 1753-1779
Author(s):  
Marta Pischiutta ◽  
Aybige Akinci ◽  
Elisa Tinti ◽  
André Herrero
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Ground Motions ◽  
Central Italy ◽  
Broad Band ◽  
Stochastic Simulations ◽  
Corner Frequency ◽  
Finite Fault ◽  
Seismic Design Code ◽  
Hybrid Simulations

SUMMARY On 24 August 2016 at 01:36 UTC a ML6.0 earthquake struck several villages in central Italy, among which Accumoli, Amatrice and Arquata del Tronto. The earthquake was recorded by about 350 seismic stations, causing 299 fatalities and damage with macroseismic intensities up to 11. The maximum acceleration was observed at Amatrice station (AMT) reaching 916 cm s–2 on E–W component, with epicentral distance of 15 km and Joyner and Boore distance to the fault surface (RJB) of less than a kilometre. Motivated by the high levels of observed ground motion and damage, we generate broad-band seismograms for engineering purposes by adopting a hybrid method. To infer the low frequency seismograms, we considered the kinematic slip model by Tinti et al . The high frequency seismograms were produced using a stochastic finite-fault model approach based on dynamic corner-frequency. Broad-band synthetic time-series were therefore obtained by merging the low and high frequency seismograms. Simulated hybrid ground motions were compared both with the observed ground motions and the ground-motion prediction equations (GMPEs), to explore their performance and to retrieve the region-specific parameters endorsed for the simulations. In the near-fault area we observed that hybrid simulations have a higher capability to detect near source effects and to reproduce the source complexity than the use of GMPEs. Indeed, the general good consistency found between synthetic and observed ground motion (both in the time and frequency domain), suggests that the use of regional-specific source scaling and attenuation parameters together with the source complexity in hybrid simulations improves ground motion estimations. To include the site effect in stochastic simulations at selected stations, we tested the use of amplification curves derived from HVRSs (horizontal-to-vertical response spectra) and from HVSRs (horizontal-to-vertical spectral ratios) rather than the use of generic curves according to NTC18 Italian seismic design code. We generally found a further reduction of residuals between observed and simulated both in terms of time histories and spectra.

Numerical Surrogate Model of a Coupled Tank-Piping System for Seismic Fragility Analysis With Synthetic Ground Motions

2019 ◽  
Author(s):  
Rocco di Filippo ◽  
Giuseppe Abbiati ◽  
Osman Sayginer ◽  
Patrick Covi ◽  
Oreste S. Bursi ◽  
...  
Keyword(s):  
Finite Element ◽  
Ground Motion ◽  
Ground Motions ◽  
Fragility Analysis ◽  
Seismic Fragility ◽  
Piping System ◽  
Motion Model ◽  
Meta Model ◽  
Ground Motion Model ◽  
Hybrid Simulations

Abstract Seismic risk evaluation of coupled systems of industrial plants often needs the implementation of complex finite element models to consider their multicomponent nature. These models typically rely on significant computational resources. Moreover, the relationships between seismic action, system response and relevant damage levels are often characterized by a high level of nonlinearity, thus requiring a solid background of experimental data. Furthermore, fragility analyses depend on the adoption of a significant number of seismic waveforms generally not available when the analysis is site-specific. To propose a methodology able to manage these issues, we present a possible approach for a seismic reliability analysis of a coupled tank-piping system. The novelty of this approach lies in the adoption of artificial accelerograms, FE models and experimental hybrid simulations to evaluate a surrogate meta-model of our system. First, to obtain the necessary input for a stochastic ground motion model able to generate synthetic ground motions, a disaggregation analysis of the seismic hazard is performed. Hereafter, we reduce the space of parameters of the stochastic ground motion model by means of a global sensitivity analysis upon the seismic response of our system. Hence, we generate a large set of synthetic ground motions and select, among them, a few signals for experimental hybrid simulations. In detail, the hybrid simulator is composed by a numerical substructure to predict the sliding response of a steel tank, and a physical substructure made of a realistic piping network. Furthermore, we use these experimental results to calibrate a refined ANSYS FEM. More precisely, we focus on tensile hoop strains in elbow pipes as a leading cause for leakage, monitoring them with strain gauges. Thus, we present the procedure to evaluate a numerical Kriging meta-model of the coupled system based on both experimental and finite element model results. This model will be adopted in a future development to carry out a seismic fragility analysis.

Verocytotoxin-producing Escherichia coli infection: The Hong Kong experience

1998 ◽  
Vol 13 (11-s4) ◽  
pp. S289-S293 ◽  
Author(s):  
SSY WONG ◽  
WC YAM ◽  
PHM LEUNG ◽  
PCY WOO ◽  
KY YUEN
Keyword(s):  
Escherichia Coli ◽  
Hong Kong ◽  
Escherichia Coli Infection
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